Replaceable drill tooth



Sept. 18, 1934. F. MCLAUGHLIN REPLACEABLE DRILL TOOTH K Original F i led Sept. 20.1932

IV- Z auyfi Zin Patented Sept. 18, 1934 Application September 20,1932, Serial No. 634,043 Renewed February 12, 1934 1 Claim. (Cl. 255-69) This invention relates to drills and more particularly to an improved tooth for use with drills in coal mining and claydrilling, or the like.

An object of this invention is to provide an improved tooth construction for drill heads whereby the tooth can be readily removed from the head of the drill.

Another object of this invention is to provide a tooth construction wherein the cutting portion of the tooth is offset from the body thereof and from the head of the drill.

A further object of this invention is to provide a tooth of this kind wherein the center of the cutting portion of the tooth is in substantial alinement with the longitudinal axis of the shank so that when the tooth is sharpened or when it becomes worn, the size of the bore made by the drill will not be greatly reduced on account of the wearing or sharpening of the tooth or bit.

A still further object of this invention is to provide a tooth or bit which is adapted to be constructed out of bar metal of square cross sectional configuration, the construction permitting the formation of the bit or tooth by either bending it so as to offset the cutting portion from the shank or by forging or otherwise forming the tooth or hit with the oifset portion and at the same time curving the bit longitudinally so as to provide the desired angle for the cutting end of the tooth or bit when mounted in the head of the drill.

The above and various other objects and advantages of this invention will in part be described and in part be understood from the following detailed description of the present preferred embodiment, the same being illustrated in the accompanying drawing wherein:-

Figure 1 is a detail side elevation of a drill head shown in fragmentary form having teeth or bits constructed according to the preferred embodiment of this invention mounted therein, the drill head being broken away and partly in section to show the manner of removably securing the teeth or bits in the head.

Figure 2 is a detail rear elevation of one form of the tooth or bit removed from the drill head.

Figure 3 is a detail side elevation of the bit shown in Figure 2.

Figure 4 is a detail rear elevation of another form of this tooth 01' bit.

Figure 5 is a detail side elevation of the bit shown in Figure 4.

Referring to the drawing wherein like characters of reference designate corresponding parts throughout the several views, the letter H designates generally a drill head such as is used at the present time in coal mining operations or in drilling through clay or the like. This drill head H is provided at the working end thereof with a socket 13 which is of tapering construction, the socket being larger at the working end than at the inner end, and a wedge, generally designated as 10, is adapted to be mounted in this bit holding or tooth holding socket 13.

This wedge 10 is provided with a base 11 and a tapering central portion or bit clamping member 12, and the shanks 14 of a pair of bits or teeth 15 are adapted to be engaged one on each side of the tapering portion 12 of the bit tightening member 10. The wedge 12 of the member 10 is adapted to force the shanks 14 of the teeth or bits 15 against the side walls of the tapering sockets 13 so as to frictionally hold the bits 15 within the head H. This manner of securing the bits 15 within the head H is of well known construction, and further description thereof is believed unnecessary.

The bits or teeth members 15, as shown in Figures 2 and 3, are constructed from a single bar of metal which is square in cross section, and the cutting end portion 16 of the bit 15 is disposed on an angle to the longitudinal axis of the shank 14, and the intermediate portion 17 between the cutting end 16 and the shank 14 provides a shoulder which offsets the cutting end portion 16 from the shank 14.

This cutting end 16 is so positioned relative to the drill head H that as the cutting end portion 16 wears down by either the sharpening of the bit or by contact with the material, the forward or cutting end portion 16 will wear down on a line substantially parallel with the longitudinal axis of the drill head H. In this manner, as the cutting end portion 16 wears down, the size of the bore formed by the bits 15 will not be greatly reduced as is customary where these bits are of straight construction and are, therefore, disposed on an angle to the longitudinal axis of the drill head H.

The transverse center of the cutting end portion 16 is substantially in alinement with the longitudinal axis of the shank 14 although the body of the cutting end portion 16 is ofiset and disposed on an angle to the longitudinal axis of the shank 14. By offsetting the tooth portion 16 from the shank 14 and constructing the cutting portion 16 with the center thereof in alinement with the center of the shank 14, the strain applied to the bit or tooth 15 will be equally distributed throughout the body of the shank 14.

In Figures 4 and 5, there is disclosed a modified form of the bit or tooth wherein the bit 15 is provided with a shank 14 which is square in cross sectional configuration and the cutting end portion 16' has one edge portion thereof in alinement with an adjacent edge of the shank 14. The head portion 16 of the bit 15 on one side thereof is offset, as at 18, so as not only to increase the cutting head 16' but also to provide the desired angle of clearance on the outer edge portion 19 of the head 16. This angle 19 is substantially equal to the angle of the head portion 16 of the bit member 15 so that when this bit 15 is mounted in the head H, the cutting head portion 16 will be disposed on substantially the same angle as the bit 15. Furthermore, as the bit 15 is cut back through sharpening or becomes worn down, the wearing through the sharpening or usage will not greatly reduce the size of the bore formed by the bits 15.

As shown in Figures 3 and 5, the bits 15 and 15' are curved longitudinally so that the desired cutting clearance will be provided when the bit is mounted within the head H. This longitudinal curvature taken in combination with the ofiset cutting head 16 or 16 provides a bit construction which will greatly facilitate the cutting of material such as coal, clay or the like.

By constructing the tooth 15 as shown in Figure 3, and the tooth 15' as shown in Figure 5, when either of these teeth are mounted in the drill head H, the cutting end portions 16 and 16', respectively, will be directed in the direction of the rotation of the drill, which construction provides a stronger tooth and facilitates the cutting action of the tooth when mounted in the head H. As seen in side elevation, the tooth 15 will have the cutting end portion 16 directed toward the longitudinal axis of the head H.

It is, of course, understood that various changes and modifications may be made in the details or construction and design of the above specifically described embodiment of this invention without departing from the spirit thereof, such changes and modifications being restricted only by the scope of the following claim.

What is claimed is:-

A drill bit comprising a shank, a cutting head, and means for connecting'the head with the shank and ofisetting the head on an angle to the shank whereby the transverse center of the forward end of the head is disposed in substantial alinement with the longitudinal axis of the shank.

FRED MCLAUGI-ILIN. 

